This invention relates in general to vehicle power steering systems, and in particular to a belt tensioner for use with an electric power steering system.
Virtually all vehicles include steering systems in which the driver of the vehicle turns the vehicle wheels via rotation of a steering wheel. Sometimes, rotation of the steering wheel rotates a steering column which is connected to a steering gear assembly. The steering gear assembly is coupled to the vehicle wheels. Rotation of the steering wheel to adequately turn the vehicle may be difficult depending on various factors, such as the speed of the vehicle and the mechanical coupling of the steering system. Therefore, many vehicles include power assisted steering systems which assist the driver in steering the vehicle.
One traditional steering system includes hydraulic components, such as valves and cylinders, which apply a hydraulic force to the steering gear assembly to assist in turning the vehicle wheels. Movement of the steering column actuates the valves and cylinders to apply an appropriate amount of assisting force.
Another type of power steering system is an electric power steering system in which the assisting force is derived from the output of an electric motor. A sensor is connected to the steering wheel or steering column to determine the desired assisted force which is delivered by the electric motor. The electric power steering system may be configured such that the output of the electric motor acts upon the steering wheel column or components of the steering gear assembly to provide the assisting force.
Many different drive mechanisms can be used to transfer the output of the electric motor to the steering gear assembly. For example, some systems use direct gear drive mechanisms in which the output shaft of the electric motor is coupled to a pinion gear which is in meshed engagement with one or more gears connected to the steering gear assembly. Another method is to use a couple of pulleys connected together by a flexible belt or chain. One pulley is connected to the output of the electric motor, and the other pulley is connected to the steering gear assembly. Although the use of a flexible belt is generally sufficient, under certain conditions such as abrupt directional changes and sudden rotational movements, portions of the belt may slacken and possibly slip relative to the pulleys.